My friend did arenas with his 10 warlocks (specced demonology) back in cataclysm. While he never got over 1200 rating, he did do well enough to cap points and get decent enough gear to do some fun world pvp. I was also able to do the same with my 5 feral druids (it was quite fun for about half a season when swipe was buffed and could almost global an enemy team if they were bunched up!). Either way neither of us really took it seriously enough to get a decent rating but we did have fun.